JP6677148B2 - Press forming method of metal plate - Google Patents

Description

  The present invention relates to a method for press-forming a metal plate.

  Patent Document 1 discloses a method for manufacturing a metal separator for a fuel cell. This separator is formed by press-forming a metal material plate. Press molding is performed in two steps of primary molding (temporary molding) and secondary molding (main molding). In each of the upper mold and the lower mold used for the primary molding, convex ridges having curved tops and grooves are provided alternately. During press molding, the material plate is sandwiched between the upper mold and the lower mold, and the top of the ridge is pressed against the material plate so that the ridges of the upper mold and the grooves of the lower mold engage. Then, the material plate is formed with irregularities as a gas flow path.

JP 2005-243252 A

  In general, it is preferable that a separator for a fuel cell has a flat top surface of a convex portion in order to secure conductivity. However, in the above-described conventional technology, the convex portion of the primary molding die has an R shape (a shape having a curved top), so that the top surface of the convex portion of the material plate after the primary molding has a curved surface. turn into. For this reason, it is difficult to return the curved top surface to a flat surface by secondary molding. Such a problem is not limited to the press forming of the separator for the fuel cell, and is a problem that occurs in the press forming of another type of metal plate.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following embodiments.
A method for press-forming a metal plate, comprising: (i) press-forming the metal plate using a first temporary forming die and a second temporary forming die for temporary forming; A first pressing step of obtaining a formed metal plate; and (ii) a second pressing step of further press-forming the temporarily formed metal plate by using a first forming die and a second forming die for the main forming. Press step, wherein the first temporary forming mold includes a first convex portion having a planar top portion that contacts the metal plate and presses the metal plate in the first press step, and The temporary forming die includes a first concave portion at a position facing the first convex portion, and the first convex portion and the first concave portion are disposed between the metal plate and the first plate in a bottom dead center state of the first pressing step. A gap is left between the first mold and the first recess. A second convex portion for pressing a concave surface of the streaks extending in the streak-like shape of the temporarily formed metal plate in the lessening step, and a top of the second convex portion is provided on both side ends of the top and the second convex portion is provided. A protrusion protruding toward the main mold, and a concave top provided between the protrusions on both side ends, wherein the protrusion contacts the concave surface of the temporarily formed metal plate. Then, the temporarily formed metal plate is pressed, and the second main mold has a second concave portion having a planar bottom at a position facing the second convex portion, and the second convex portion has a second concave portion. The second concave portion is configured such that the metal plate is in contact with the bottom portion of the second concave portion in a bottom dead center state of the second pressing step, and is provided at both side ends of a top portion of the second convex portion. The provided protrusions and the concave top provided between the protrusions are used in the second pressing step. The portion of the metal plate pressed by the protrusions provided on both side ends of the top of the second protrusion and the concave top provided between the protrusions is substantially flat. A method for press-forming a metal plate, wherein the method comprises:

(1) According to one aspect of the present invention, there is provided a method for press-forming a metal plate. The press forming method of the metal plate includes: (i) press forming the metal plate using a first temporary forming die and a second temporary forming die for temporary forming, thereby forming a temporary forming having streaky extending irregularities. A first pressing step of obtaining a pressed metal plate, and (ii) a second press for further press-forming the temporarily formed metal plate using a first and a second forming die for the main forming. And a step. The first temporary forming die includes a first convex portion having a planar top portion that contacts the metal plate and presses the metal plate in the first pressing step, and the second temporary forming die includes the first temporary forming die. A first concave portion is provided at a position facing the one convex portion, and the first convex portion and the first concave portion are located between the metal plate and the first concave portion in a bottom dead center state of the first pressing step. It is configured such that a gap remains. The first molding die includes a second convex portion that presses a concave surface of the streaks extending in the stitch-like shape of the temporarily formed metal plate in the second pressing step, and a top portion of the second convex portion is A projection provided on both side ends of the top and projecting toward the second main mold, and a concave top provided between the projections on the both sides; The temporary molding metal plate is brought into contact with the concave surface of the metal molding, and presses the temporary molding metal plate. The second molding die has a flat bottom at a position facing the second convex portion. The second convex portion and the second concave portion are configured such that the metal plate is in contact with the bottom of the second concave portion in a bottom dead center state of the second pressing step.

  According to the press forming method for a metal plate of this embodiment, the flat top of the first convex portion comes into contact with the metal plate and presses the metal plate in the first pressing step as temporary forming, so that the metal plate is pressed as in the prior art. The top surface (convex surface) of the convex portion of the temporarily formed metal plate can be made flatter than in the case where the convex ridge portion of the mold has an R shape. In addition, since the metal plate is in contact with the flat bottom of the second concave portion of the second main mold in the second pressing step as the main molding, the top surface of the convex portion of the metal plate after the main molding is also compared with the conventional technology. Can be flattened.

  The present invention can be realized in various forms other than the above. For example, it can be realized in the form of a metal plate press-molding die or the like.

Explanatory drawing of the separator formed by the press molding method of embodiment. The figure which shows an example of a press molding machine. Sectional drawing explaining the change of the metal plate at the time of performing press molding. Sectional drawing of a 1st temporary molding die, a 2nd temporary molding die, and a metal plate in a 1st press process. Sectional drawing of a 1st temporary molding die, a 2nd temporary molding die, and a metal plate. The expanded sectional view of a 1st temporary forming die, a 2nd temporary forming die, and a metal plate. FIG. 5 is a cross-sectional view of a first main mold, a second main mold, and a metal plate in a second pressing step. Sectional drawing of a 1st main molding die, a 2nd main molding die, and a metal plate. FIG. 3 is an enlarged cross-sectional view of a first main mold, a second main mold, and a metal plate.

  FIG. 1 is an explanatory diagram of a fuel cell separator 50 formed by a metal plate press forming method according to an embodiment of the present invention. In FIG. 1, the X direction is the longitudinal direction of the separator 50, the Y direction is the short direction of the separator 50, and the Z direction is the thickness direction of the separator 50.

  At one longitudinal edge of the separator 50, a fuel gas manifold hole 62, a cooling medium manifold hole 84, and an oxidizing gas manifold hole 72 are provided in order from top to bottom. . On the other hand, at the other end, an oxidizing gas manifold hole 74, a cooling medium manifold hole 82, and a fuel gas manifold hole 64 are provided in order from top to bottom. . At the center of the separator 50, a plurality of streaks extending in the form of stripes are provided, and the recesses form the gas passage 54. “Streak” means an elongated linear shape. The streak-shaped concave portion on the back surface side of the gas flow path 54 is used as a cooling medium flow path. These manifold holes 62, 64, 72, 74, 82, 84 and the gas flow passage 54 are formed by press molding. Hereinafter, press forming of the gas flow passage 54 will be described. However, the openings of the manifold holes 62, 64, 72, 74, 82, 84 may be performed in the same step as the formation of the gas flow passage 54.

  FIG. 2 is a diagram illustrating an example of the press molding machine 100 according to the present embodiment. The press molding machine 100 includes a driving unit 110, a slide bar 120, a first molding die 210 (upper die), and a second molding die 220 (lower die). The drive unit 110 moves the slide bar 120 up and down as shown by the arrows. A first molding die 210 is attached to the lower end of the slide bar 120. On the lower surface of the first molding die 210, convex portions 310 and concave portions 320 are provided alternately. The second molding die 220 is installed on the base 130, and the convex portions 410 and the concave portions 420 are provided alternately on the upper surface thereof.

  This press molding machine 100 is a primary molding machine used for primary molding of a flat metal plate 50a. The metal sheet after the primary forming is secondarily formed by a secondary forming machine. The configuration of the secondary molding machine is almost the same as that of the primary molding machine except for the shape of the mold, and thus the description is omitted. In this specification, the primary molding is referred to as “temporary molding” or “first pressing step”, and the secondary molding is referred to as “main molding” or “second pressing step”.

  FIG. 3 is a cross-sectional view illustrating a change in the material metal plate 50a when performing the first pressing step and the second pressing step. The raw metal plate 50a forms a temporarily formed metal plate 50b having a concave surface R1 and a convex surface P1 by a first pressing process that is a temporary forming. The back side of the concave surface R1 and the convex surface P1 is a convex surface P2 and a concave surface R2. The difference in height between the concave surface R1 of the temporarily formed metal plate 50b and the adjacent convex surface P1 (the depth of the concave surface R1) is D1. The temporarily formed metal plate 50b forms a fully formed metal plate 50c having concave surfaces R3, R4 and convex surfaces P3, P4 by a second pressing step which is the main forming. The height difference (depth of the concave surface R3) D2 between the concave surface R3 of the main formed metal plate 50c and the adjacent convex surface P3 is larger than the depth D1 of the concave surface R1 of the temporarily formed metal plate 50b. The concave portion on the upper surface of the molded metal plate 50c is used, for example, as a gas channel 54, and the concave portion on the lower surface is used as a cooling medium channel.

  FIG. 4 is a view for explaining the first pressing step, and illustrates a cross-sectional view of a first temporary forming die 210a, a second temporary forming die 220a, and a part of the raw metal plate 50a. This cross-sectional view shows a cross section (YZ cross section) perpendicular to the direction in which the gas flow path 54 extends in FIG. Hereinafter, the same applies to the cross-sectional views of FIGS. In the first pressing step, the raw metal plate 50a is press-formed using the first temporary forming die 210a and the second temporary forming die 220a for temporary forming. The first temporary forming die 210a includes a convex portion 310a (first convex portion) and a concave portion 320a. The second temporary forming die 220a includes a concave portion 420a (first concave portion) and a convex portion 410a at positions facing the convex portion 310a and the concave portion 320a of the first temporary forming die 210a, respectively. In the first temporary forming die 210a, the convex portion 310a comes into contact with the material metal plate 50a and presses the material metal plate 50a.

  FIG. 5 is an explanatory diagram of a state of the bottom dead center of the press forming machine 100 (FIG. 2) in the first pressing step. “Bottom dead center” means the end position of the stroke of the press molding machine 100. The “bottom dead center state” is a state in which the distance between the two molds 210a and 220a is minimum. The raw metal plate 50a in FIG. 4 is deformed by the pressing of the convex portion 310a of the first temporary forming die 210a to form a temporary formed metal plate 50b having irregularities.

  FIG. 6 is an enlarged cross-sectional view of a portion sandwiched between the broken lines depicted in FIG. 5, and is a diagram illustrating the uneven shape of one pitch PT of the first temporary molding die 210a and the second temporary molding die 220a. The convex portion 310a of the first temporary forming die 210a has a flat top Ap1. Side walls 510a on both sides of the convex portion 310a of the first temporary forming die 210a have an S-shape, and one end thereof is connected to the top Ap1. The other end of the side wall 510a is connected to the planar bottom of the recess 320a of the first temporary forming die 210a. Similarly, the convex portion 410a of the second temporary forming die 220a also has a flat top Ap2. Side walls 520a on both sides of the convex portion 410a of the second temporary forming die 220a have an S-shaped shape, and one end thereof is continuous with the top Ap2. The other end of the side wall 520a is connected to the planar bottom of the recess 420a of the second temporary forming die 220a. The bottoms of the recesses 320a and 420a of the two molds 210a and 220a do not need to be flat because they do not contact the temporarily formed metal plate 50b.

  In the first pressing step, the top Ap1 of the convex portion 310a of the first temporary forming die 210a contacts one surface of the raw metal plate 50a (FIG. 4) and presses the raw metal plate 50a, and the convex portion of the second temporary forming die 220a is pressed. The top Ap2 of the portion 410a contacts the other surface of the material metal plate 50a and supports the material metal plate 50a. By doing so, the flat surfaces of the concave surfaces R1 and R2 (FIG. 3) of the temporarily formed metal plate 50b contacting these tops Ap1 and Ap2 are different from the case where the convex ridges of the mold are formed in an R shape as in the prior art. The state can be maintained, and the flat state of the convex surfaces P2 and P1 on the back side of the concave surfaces R1 and R2 can be maintained. Further, compared to the related art, it is possible to suppress a decrease in the thickness of the temporarily formed metal plate 50b at the center of the concave surfaces R1 and R2.

  In the bottom dead center state of the first pressing step, between the temporary forming metal plate 50b and the concave portion 320a of the first temporary forming die 210a, and between the temporary forming metal plate 50b and the concave portion 420a of the second temporary forming die 220a. , A gap G1 remains. Also, between the temporary forming metal plate 50b and the side wall 510a of the convex portion 310a of the first temporary forming die 210a, and between the temporary forming metal plate 50b and the side wall 520a of the convex portion 410a of the second temporary forming die 220a. , The gap G2 remains. This can prevent the metal plate from being deformed into an undesired shape due to variations in the shape and assembly of the mold, variations in the thickness of the metal plate, and the like. In FIG. 6, a center line CL1 passing through the center between the inner surface of the first temporary forming die 210a and the inner surface of the second temporary forming die 220a is drawn. The center line CL1 will be described later.

  FIG. 7 is a view for explaining the second pressing step, and shows a state immediately before the pressing of the temporarily formed metal plate 50b is started. In the second pressing step, the temporarily formed metal plate 50b obtained in the first pressing step is press-formed using the first main forming die 210b and the second main forming die 220b. The first main mold 210b includes a convex portion 310b (second convex portion) and a concave portion 320b. The second main molding die 220b includes a concave portion 420b (second concave portion) and a convex portion 410b at positions facing the convex portion 310b and the concave portion 320b of the first main molding die 210b, respectively. The first molding die 210b is disposed on the second molding die 220b such that the concave surface R2 of the temporary molding metal plate 50b is in contact with the projection 410b of the second molding die 220b. The provisionally formed metal plate 50b is pressed in contact with the concave surface R1 of the formed metal plate 50b.

  FIG. 8 is an explanatory diagram of a state of the bottom dead center of the press forming machine 100 (FIG. 2) in the second pressing step. The temporarily formed metal plate 50b in FIG. 7 is further deformed by the pressing of the convex portion 310b of the first final molding die 210b, and forms the final molded metal plate 50c.

  FIG. 9 is an enlarged cross-sectional view of a portion sandwiched by the broken lines depicted in FIG. 8, and is a diagram illustrating the uneven shape of one pitch PT of the first main mold 210b and the second main mold 220b. The length of one pitch PT is equal to the length of one pitch PT in FIG. The tops of the projections 310b of the first molding die 210b are provided on both side ends of the tops, and the projections 610 protruding toward the second molding die 220b, and the concave tops provided between the two projections 610 are provided. 710. Side walls 510b on both sides of the convex portion 310b of the first main mold 210b have an S-shape, and one end thereof is connected to the protruding portion 610, respectively. The other end of the side wall 510b is connected to the bottom Bo1 of the recess 320b of the first main mold 210b.

  The tops of the protrusions 410b of the second main mold 220b are provided on both side ends of the tops and protruded toward the first main mold 210b, and the concave top provided between the two protrusions 620. 720. Side walls 520b on both sides of the convex portion 410b of the second main mold 220b have an S-shape, and one end thereof is connected to the protruding portion 620, respectively. The other end of the side wall 520b is connected to the bottom Bo2 of the concave portion 420b of the second main mold 220b.

  In the second pressing step, the projection 610 of the projection 310b of the first main mold 210b contacts the concave surface R1 of the temporarily formed metal plate 50b (FIG. 7) and presses the temporarily formed metal plate 50b. In this case, the frictional resistance between the temporarily formed metal plate 50b and the convex portion 310b can be reduced as compared with the case where the entire convex portion 310b of the first full molding die 210b is pressed. The same applies to the protrusion 410b of the second main mold 220b.

  In FIG. 9, the bottom Bo1 of the concave portion 320b of the first final molding die 210b is planar, and the bottom Bo2 of the concave portion 420b of the second final molding die 220b is also planar. In the lower dead center state of the second pressing step, the main forming metal plate 50c is in contact with the bottom Bo1 of the concave portion 320b of the first main forming die 210b and the bottom Bo2 of the concave portion 420b of the second main forming die 220b, respectively. . By doing so, the flat surfaces of the convex surfaces P3, P4 (FIG. 3) of the main formed metal plate 50c that are in contact with these bottom portions Bo1, Bo2 can be maintained. In addition, since the projections 610 and 620 of the projections 310b and 410b respectively press down both ends of the concave surfaces R3 and R4 (FIG. 3) of the main formed metal plate 50c, the flatness of the projections P3 and P4 can be further improved.

  In FIG. 9, between the main forming metal plate 50c and the concave top portion 710 of the convex portion 310b of the first main forming die 210b, and between the main forming metal plate 50c and the concave top portion 720 of the convex portion 410b of the second main forming die 220b. A gap G3 is formed between. Further, between the main forming metal plate 50c and the side wall 510b of the convex portion 310b of the first main forming die 210b, and between the main forming metal plate 50c and the side wall 520b of the convex portion 410b of the second main forming die 220b. , A gap G2 is formed. This can prevent the metal plate from being deformed into an undesired shape due to variations in the shape and assembly of the mold, variations in the thickness of the metal plate, and the like.

  In FIG. 9, a center line CL2 passing through the center between the inner surface of the first main mold 210b and the inner surface of the second main mold 220b is depicted. The center line CL1 between the first temporary forming die 210a and the second temporary forming die 220a in the first pressing step of FIG. 6 is shorter than the center line CL2 of FIG. By doing so, it is possible to suppress the occurrence of large springback in the temporarily formed metal plate 50b (FIG. 6) due to excessive deformation in the first pressing step.

  As described above, in the present embodiment, in the first pressing process as the temporary forming, the planar top Ap1 of the convex portion 310a of the first temporary forming die 210a comes into contact with the material metal plate 50a, and the material metal plate 50a is removed. Since the pressing is performed, the convex surfaces P1 and P2 of the temporarily formed metal plate 50b can be flattened as compared with the case where the convex ridge portion of the mold is formed in an R shape as in the related art. Further, in the second pressing step as the main forming, the temporarily formed metal plate 50b comes into contact with the bottom Bo2 of the concave portion 420b of the second main forming die 220b by pressing. It can be made flatter.

・ Modification:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

-Modification 1
In the above embodiment, the first and second pressing steps are used for press-forming the fuel cell separator 50, but may be used for press-forming other types of metal plates. In the press forming of other types of metal plates, the convex surface of the metal plate can be flattened as compared with the related art.

・ Modification 2:
In the above embodiment, press molding was performed using the first mold 210 as an upper mold and the second mold 220 as a lower mold. However, the first mold 210 was used as a lower mold, and the second mold 220 was used as an upper mold. It may be.

  The present invention is not limited to the above-described embodiments and modified examples, and can be implemented with various configurations without departing from the spirit thereof. For example, the embodiments corresponding to the technical features in each mode described in the summary of the invention, the technical features in the modified examples are for solving some or all of the above-described problems, or In order to achieve some or all of the effects, replacement and combination can be performed as appropriate. Unless the technical features are described as essential in the present specification, they can be deleted as appropriate.

50: Separator 50a: Material metal plate 50b: Temporarily formed metal plate 50c: Mainly formed metal plate 54: Gas flow passages 62, 64 ... Manifold holes for fuel gas 72, 74 ... Manifold holes for oxidant gas 82, 84 ... Cooling medium Manifold hole 100 ... Press molding machine 110 ... Drive section 120 ... Slide bar 130 ... Base 210 ... First molding die 210a ... First temporary molding die 210b ... First full molding die 220 ... Second molding die 220a ... Second Temporary forming die 220b ... Second main forming die 310, 310a, 310b ... Convex part 320, 320a, 320b ... Concave part 410, 410a, 410b ... Convex part 420, 420a, 420b ... Concave part 510a, 510b ... Side wall 520a, 520b ... Side wall 610, 620: Projecting portion 710, 720: Recessed top

Claims (1)

A press forming method for a metal plate,
(I) A first press for obtaining a temporarily formed metal plate having streaks extending by pressing the metal plate using a first temporary forming die and a second temporary forming die for temporary forming. Process and
(Ii) a second pressing step of further press-forming the temporarily formed metal plate using a first molding die and a second molding die for full molding;
With
The first temporary forming die includes a first convex portion having a planar top portion that contacts the metal plate and presses the metal plate in the first pressing step,
The second temporary forming mold includes a first concave portion at a position facing the first convex portion, and the first convex portion and the first concave portion are configured such that the metal is formed at a bottom dead center of the first pressing step. A gap is left between the plate and the first recess,
The first molding die includes a second convex portion that presses a concave surface of the streaks extending in the stitch-like shape of the temporarily formed metal plate in the second pressing step, and a top portion of the second convex portion is A projection provided on both side ends of the top and projecting toward the second main mold, and a concave top provided between the projections on the both sides; Pressing the temporarily formed metal plate in contact with the concave surface of the temporarily formed metal plate,
The second molding die includes a second concave portion having a planar bottom portion at a position facing the second convex portion, and the second convex portion and the second concave portion are formed under the second pressing step. In the dead point state, the metal plate is configured to contact the bottom of the second recess ,
The protrusions provided on both side ends of the top of the second protrusion and the concave top provided between the protrusions are the second protrusions of the metal plate in the second pressing step. and the projection portion provided at both side ends of the top parts, and a concave top portion provided between said projections, the pressed portion is, that is configured to be substantially flat,
Press forming method for metal plate.

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